In a nutshell, what you do is fold and tie up the shirts (or whatever), soak them in a solution of soda ash and water for a few minutes, apply a solution of dye, water and urea, let them sit overnight in plastic bags, rinse them, untie them, rinse them some more, and wash them in a washing machine with synthrapol and hot water. Thats it! Easy!
The Dharma group kits have all the basics except the clothing, which we carry at very reasonable prices. Dharma white clothing is 100% cotton and tie-dyes beautifully. If you get your clothing elsewhere, make sure it's not a polyester blend! You'll get a very washed out look.
Other odds and ends you will need are: large tables covered with plastic (card tables or picnic tables work) buckets for the soda ash solution (plastic, stainless or enamel) old newspapers (at least 3 months old-so the ink doesn't come off) to absorb the excess dye under the clothing being tie-dyed bowls of water to rinse fingers between colors measuring cups-2 cups or larger-clear pyrex works great measuring spoons and spoons for stirring the dyes a funnel - to pour premixed dye solution into squirt bottles paper towels and/or sponges to wipe up messes! Big garbage can for trash
Optional things: